Why refactoring getQuotes to async/await doesn't work?

Question

```javascript
const getQuotes = async () =>  fileSystem.readFile('data.json', 'utf8', (err, data) => {
        if (err) {
             return err;
        }
        else {
            const quotes = JSON.parse(data);
            return quotes;
        }
    });
(async () => {
    const q = await getQuotes();
    console.log( q);
})();
```
Console:

Promise { undefined }

Brendan Whiting · Accepted Answer

The readFile method doesn't return anything. If you have a function that takes a callback, and you want it to return a promise, one strategy is to wrap it in a Promise constructor (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise), which takes a function with two arguments, resolve and reject. You can call resolve() on the successful response and reject() on the error.
JavaScript
const getQuotes = () =>  {
    return new Promise((resolve, reject) => {
        fileSystem.readFile('data.json', 'utf8', (err, data) => {
            if (err) {
                 return reject(err);
            } else {
                const quotes = JSON.parse(data);
                return resolve(quotes);
            }
        })
    })
}

You can also use a neat utility function called promisify (https://medium.com/@suyashmohan/util-promisify-in-node-js-v8-d07ef4ea8c53)

Vitaly Khe · Answer

Got it, thanks

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Vitaly Khe

Vitaly Khe

Why refactoring getQuotes to async/await doesn't work?

2 Answers

Brendan Whiting

Brendan Whiting

karan Badhwar

karan Badhwar

Vitaly Khe

Vitaly Khe